Mercury 7 astronauts Gordon Cooper (from left), Wally Schirra and Carpenter at a press conference at Kennedy Space Center in 1998. The three were in Florida to watch the launch of the Shuttle Discovery, which carried 77-year-old Glenn into orbit

Scott Carpenter, the fourth American astronaut to fly in space and the second to orbit Earth, died on Thursday, a NASA official tells NPR.

Carpenter, an original Mercury 7 astronaut, was 88.

NPR's Russell Lewis filed this report for our Newscast unit:

"Scott Carpenter's 1962 flight was just five hours, and his mission was to determine how well humans could function in weightlessness. His capsule circled the Earth three times before returning for a parachute landing.

"Carpenter was about 250 miles off-course because of a technical malfunction. He would never fly in space again. Remembering his mission, in 2012, he realized that now humans are in survival mode.

"We've got to take care of the resources we have on this planet, because there's no resupply possible," he said at the time.

"His death leaves John H. Glenn Jr., who flew the first orbital mission on Feb. 20, 1962, and later became a United States senator from Ohio, as the last survivor of the Mercury 7.

"When Lieutenant Commander Carpenter splashed down off Puerto Rico in his Aurora 7 capsule on May 24, 1962, after a harrowing mission, he had fulfilled a dream.

" 'I volunteered for a number of reasons,' he wrote in We Seven, a book of reflections by the original astronauts published in 1962. 'One of these, quite frankly, was that I thought this was a chance for immortality. Pioneering in space was something I would willingly give my life for.' "

Update at 5:13 p.m. ET. The Mission:

For his obituary on All Things Considered, Russell focuses on Carpenter's one and only time in space.

In the '60s, Russell explains, space was still a mystery; humans had basic questions like: Could people function in space? Would their blood boil? Was it possible to eat?

Carpenter tried to answer many of these questions, and a packed schedule contributed to a ragged mission.

Here's a bit of Russell's script:

"Carpenter orbited the Earth three times. He barely had a moment to himself. Check blood pressure, maneuver the capsule, take celestial measurements. Carpenter got behind in the flight plan, and NASA's controllers were worried. Here he is talking to fellow astronaut Alan Shepard about his re-entry plans:

" 'How are you doing on re-entry attitude over?'

" 'Yeah, [I'm] stowing a few things first. I don't know yet.'

"During the final orbit, the engines didn't fire at the right time. It was later determined to be a technical malfunction. Carpenter's capsule splashed down 250 miles off-course. At first NASA applauded the mission but later was bothered by the blemish. This is Chris Kraft, NASA's flight director at the time, in a 2001 NPR interview:

" 'I just don't think he had an appreciation for the position he had put himself in or frankly put the space program in.'

NASA historians say that criticism is unfair. Francis French has written several books about NASA's early years.

" 'I think that's where some of the misconceptions about his flight come in, because he did try to do everything and he managed to do everything,' French said. 'But it did mean the mission didn't go 100 percent according to the checklist.' "